What the Anesthesiologist Should Know before the Operative Procedure

It is important to establish whether this this carpal tunnel repair is an acute or chronic procedure and if there is urgency in treating the patient. While this procedure is usually performed as an elective procedure, acute carpal tunnel syndrome (CTS) can occur. Elective carpal tunnel release is usually a short surgical procedure (often less than 30 minutes of surgical time), which USUALLY involves the use of a tourniquet. Expected blood loss is minimal and is often associated with mild postoperative pain. This surgery carries a low perioperative risk major complication.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

In most cases this is an elective procedure. In some instances, CTS can present acutely, usually as a result of radial fracture or direct injury to a carpal bone. Acute CTS has also been reported as a result of bleeding due to chronic lymphatic leukemia, hemophilia, bleeding from a giant call tumor of the tendon sheath, and vasculitis. In acute CTS, an immediate release increases the likelihood of a full recovery. In elective (chronic) cases, if further investigations may result in improved patient safety and perioperative care, it is reasonable to consider delaying the surgery.

Emergent: If this is an emergent procedure it is important to do this in a timely manner. Regional anesthesia is a useful consideration in this instance as is local anesthetic infiltration

Urgent: A risk-benefit analysis must be done to assess the viability of doing this procedure urgently. Again, regional anesthesia or local anesthetic infiltration can be considered.

Elective: If this is an elective procedure, there is adequate time to optimize the patient prior to surgery.

For the purpose of this chapter, we will assume that the procedure is being carried out as an elective procedure.

2. Preoperative evaluation

Inflammatory arthritis, autoimmune disease, rheumatoid disease, amyloidosis, hypothyroidism, diabetes mellitus, acromegaly, as well as long-term use of steroids and estrogens are risk factors for the development of CTS. It is estimated that 6% of patients with CTS have diabetes mellitus. Other medical conditions to assess for will be as for any patient having surgery, especially cardiac and respiratory conditions. It is important to determine if the patient has hypertension and, if so, how well this is controlled, especially if intravenous regional anesthesia (IVRA) is planned.

Delaying surgery may be indicated if any of the above conditions are present and not controlled, investigated, and optimized. Because this is usually an elective procedure, it is important that patients are not exposed to any unnecessary risks.

3. What are the implications of co-existing disease on perioperative care?

b. Cardiovascular system:

Acute/unstable conditions

These conditions should be investigated and controlled prior to an elective procedure being performed. Referral to a cardiologist should be sought. Patients giving a history of chest pain at rest that has not been investigated or unstable angina should be further investigated.

Baseline coronary artery disease or cardiac dysfunction

Goals of management are the usual for patients with cardiac conditions, keeping in mind that this surgery carries a low risk of perioperative complications. Complete history and physical examination should be performed to assess the severity of the condition. Careful preoperative instructions should be given as to their perioperative medications. All chronic antihypertensive and cardiac medications should be taken on the morning of surgery.

Antiplatelet medications should be stopped preoperatively for 5 days, and in the instance of thienopyridine derivatives they should ideally be stopped 7 to 10 days before surgery. If he patient has had coronary stents within the past year and is on antiplatelet therapy, a plan should be devised between the anesthetist, cardiologist, and surgeon regarding perioperative antiplatelet therapy, as thienopyridines may need to be continued due to a high risk of stent thrombosis in some cases. Intraoperative management of patients with underlying coronary artery disease includes optimizing oxygen supply-demand ratio. Management for patients with cardiac dysfunction should aim to control the patient's mean arterial pressure and heart rate within 20% of their baseline, maintaining a low cardiac afterload, and avoiding agents that may depress cardiac contractility.

If the patient has hypertension it is important to establish if this is controlled. If a tourniquet is being used, it is important that the systolic blood pressure is at a level below 160 mm Hg to ensure its effectiveness. If the patient has poorly controlled hypertension, this can lead to inadequate maintenance of a bloodless field and can put the patient at risk of congested limb; IVRA may not be an appropriate anesthetic option in such a case. In this instance, it may be prudent to defer the procedure until the patient has good blood pressure control or discuss the possibility with the surgeons of performing the procedure without the use of a tourniquet.

c. Pulmonary:

A history of heavy smoking, chronic obstructive pulmonary disease (COPD), or moderate to severe asthma would favor an anesthetic technique that does not involve general anesthesia.

COPD

Perioperative evaluation

History and physical examination for these patients allow assessment of the extent and control of their condition. A history of previous admissions, especially to intensive care unit, pneumonia, oxygen requirement, or steroid use suggests severe disease. An increase in anteroposterior chest diameter, decreased chest excursion, and hyper-resonance are all physical signs of significant emphysema. Tachypnea at rest and cyanosis are signs of severity. Finger clubbing may be seen in patients with chronic hypoxemia. Pulmonary function tests, arterial blood gases, and chest radiography may be helpful in planning perioperative care in patients with severe disease. It is important that patients with COPD continue taking their medications up to and including the day of surgery.

Perioperative risk reduction strategies

In patients with COPD, an anesthetic technique avoiding general anesthetic would be preferred. This will reduce the risk of adverse respiratory outcomes. Maintenance of spontaneous ventilation and noninstrumentation of their airway will reduce the incidence of postoperative respiratory complications. Local anesthetic, IVRA, and brachial plexus block are all good anesthetic options. If brachial plexus block is employed, an axillary approach is preferred since it carries essentially no risk of pneumothorax or phrenic nerve paresis. Both supraclavicular and infraclavicular approaches are associated with a low but real risk of pneumothorax. Approaches above the clavicle carry a significant risk of phrenic nerve paresis. Phrenic nerve paresis and pneumothorax (even small) may be poorly tolerated by patients with underlying respiratory compromise and should be avoided.

Reactive airway disease (asthma)

Perioperative evaluation

Management and considerations for reactive airway disease are similar to those for COPD. The main difference is that in patients with asthma, the examination of the respiratory system is usually unremarkable between asthmatic episodes. Patients with true asthma may have an allergic (IgE mediated) component to their condition. They may also have allergies to different environmental agents and medications.

Perioperative risk reduction strategies

Like patients with COPD, an anesthetic technique avoiding general anesthetic would be preferred. Local anesthesia, IVRA, and regional blocks are options for this procedure. If a brachial plexus block is planned, an axillary approach may be preferred since it carries the lowest risk of phrenic paresis or pneumothorax.

d. Renal-GI:

Perioperative evaluation

A history of renal and gastrointestinal disorders should be sought. If renal disease is suspected, a renal function blood test should be done. Patients with dialysis-dependent end-stage renal failure should have a perioperative plan in place with the nephrology service. If liver disease is suspected, a blood test looking at liver function and coagulation should be performed. Severe abnormalities in coagulation and electrolytes should be investigated if suspected and treated. In a patient with a history of gastroesophageal reflux, a regional or local anesthetic technique should be advocated with mild sedation to minimize the risk of pulmonary aspiration.

Perioperative risk reduction strategies

Usually this is an elective procedure and hence delays in order to ensure patient safety may be warranted. Patients with renal disease should be assessed and stabilized before surgery. Electrolyte abnormalities should be corrected to a suitable level before surgery. Adequate time post dialysis should be taken so that anticoagulation is no longer a problem. For patients with liver disease, coagulation abnormalities should be corrected prior to surgery. Consultation with a hepatologist may be required preoperatively.

e. Neurologic:

Acute issues

Perioperative evaluation

Acute onset of neurologic issues should be assessed for severity prior to this procedure. A full history and physical examination should be carried out. Recent onset of seizures, abnormal neurologic symptoms, unexplained limb weakness, and neuropathy (aside from median nerve compression associated with CTS) require further investigations. These would be reasons for deferring an elective procedure until such times that they are evaluated and stabilized.

Perioperative risk reduction strategies

In patients requiring emergency surgery, they should be stabilized and a risk/ benefit analysis carried out. If the procedure is an emergency, operating under local anesthesia is an option. Elective procedures should be fully evaluated and the patient should be medically optimized prior to surgery.

Chronic disease

Perioperative evaluation

Recent relapses and neuropathies should be discussed as part of their history and examination. For patients with chronic neurologic conditions not under the care of a specialist, they should be referred to neurology services.

Perioperative risk reduction strategies

Chronic medications should be continued throughout the perioperative period. As with all types of surgery in patients with epilepsy, the perioperative anticonvulsant medications should be taken as closely to the usual times as possible.

f. Endocrine:

Perioperative evaluation

History and physical examination to look for a history of diabetes, thyroid disease as well as other endocrine problems.

Perioperative risk reduction strategies

Diabetes mellitus should be controlled either by diet, oral hypoglycemics, or insulin. A perioperative plan for the patient's blood glucose management should be in place. An HbA1C will give an idea of the patient's glycemic control. The patient's blood sugar should be managed according to hospital protocol as for any diabetic patient. Thyroid disease and other endocrine abnormalities should be managed and stabilized appropriately as with all types of surgery. Patients with acromegaly should have been investigated for this condition and optimized preoperatively. It is important to remember that acromegalic patients may be difficult to intubate and hence a regional or local anesthetic technique would be favored. If the patient has adrenal insufficiency or adrenal hyperplasia that is controlled with steroids, a perioperative plan for steroids should be followed. If in doubt, endocrine consultation may be appropriate.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Perioperative evaluation

In light of the fact that this condition is more common in patients with inflammatory arthritis, amyloidosis, acromegaly, and the use of long-term estrogens and steroids, the presence of these conditions should be looked for as part of a history and physical examination. If suspected or present, they should have been investigated and optimized preoperatively.

Perioperative risk reduction strategies

In the case of inflammatory arthritis, careful airway assessment should be carried out. If the patient has rheumatoid arthritis, then a regional anesthetic or local anesthetic technique would be preferred. If there is suspicion of atlantoaxial subluxation, flexion and extension views of the atlantoaxial junction should be performed and interpreted before surgery. Amyloid should be under the treatment of a specialist dealing with amyloid and the presence of cardiac amyloid should be determined if suspected. If present, a regional or local anesthetic technique would be the preferred choice for the procedure. For patients on long-term steroids, taking their daily dose of steroids may be sufficient to prevent acute adrenal insufficiency since this is a very minor and low-risk surgical procedure. Intraoperative intravenous supplementation of steroids may be considered in patients taking high chronic doses.

4. What are the patient's medications and how should they be managed in the perioperative period?

Patients may be on a variety of medications including analgesics, vitamins, and herbal medications.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

There are no specific medications that patients having this type of surgery should be taking. Often they will be on medications for diabetes, inflammatory arthritis, long-term steroids, thyroid medications, as well as analgesics. Nonsteroidal anti-inflammatory medications do not pose any significant increase in risk of bleeding with this technique.

i. What should be recommended with regard to continuation of medications taken chronically?

Antiplatelet: There is no evidence to support discontinuing aspirin and this may be subject to an individual surgeon's preference. Discontinue clopidogrel 7 days preoperatively and ticlopidine 10 days preoperatively of the patient has not had coronary stenting within the last 12 months. If uncertain a cardiologist should be consulted. A peripheral nerve block is not contraindicated for a patient on antiplatelet therapy provided the block is performed in an area where inadvertent vascular puncture can be stopped by direct mechanical compression. An axillary block would therefore be preferred in this setting over a supraclavicular block.

Psychiatric: Continue medications perioperatively. Lithium or monoamine oxidase inhibitors (MAOIs) can be continued perioperatively as this is considered to be minor surgery. MAOIs are less common in patients in recent years. Anesthetic management for patients on lithium and MAOIs would be as for any procedure involving anesthesia. However, because this surgery can be done with a regional technique or under local anesthetic, perioperative continuation can be considered.

Ensure that all members of the staff within the operative room are aware of the latex allergy.

l. Does the patient have any antibiotic allergies - Common antibiotic allergies and alternative antibiotics

Many surgeons will not require antibiotics or this surgery.The surgeon will decide if antibiotics are required. If the patient has antibiotic allergies, ensure that the allergy is real. Find out the nature of the reaction from the patient. Ensure that appropriate alternative antibiotics are used (check if hospital has a protocol). The most common antibiotic allergy is to penicillin. It is important to remember the cross reactivity with cephalosporin. Alternative antibiotics include clindamycin, vancomycin, or erythromycin.

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia

Documented: Avoid all trigger agents such as volatile agents and succinylcholine and ensure these are removed from the operating room prior to the patient's arrival. It is preferable in this instance to avoid general anesthesia. Regardless of the anesthetic technique used, an MH cart should be immediately available.

Family history or risk factors for MH: A thorough history should elicit if the patient is at risk for the condition. If it is suspected then they should be ideally tested pre-operatively. If testing is not possible, it is safer to treat them as if they were MH positive, and a regional technique or local anesthetic technique may be the best anesthetic choice.

Local anesthetics/ muscle relaxants

If the patient has an allergy to local anesthetics it is important to determine in a history if this is to all local anesthetics and determine the names of the local anesthetics they are allergic to. If it is a true allergy, then avoidance of these agents is preferred. If the patient has no allergy to an alternative local anesthetic this may be used if appropriate. If in doubt, and the previous reaction has been severe, then general anesthetic is advised. If the patient has an allergy to muscle relaxants these should be avoided. Ideally a regional technique should be used.

5. What laboratory tests should be obtained and has everything been reviewed?

There are no specific laboratory tests recommended for patients undergoing this procedure. Blood tests will depend on the patient's history, coexisting diseases, and medications.

Hemoglobin levels: Will depend on the individual patient. If the patient has a history of cardiac disease, a higher hemoglobin level than in a fit healthy patient.

Electrolytes: Within safe range as for any type of surgery.

Coagulation panel: Ensure patient is not coagulopathic, if mild coagulopathy local anesthesia is a useful consideration or a regional technique not close to the clavicle.

Imaging and other tests: No specific imaging or other tests.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

There are several options for anesthesia for this procedure: local anesthetic infiltration, IVRA, peripheral nerve block, and general anesthesia. An awake technique (usually local anesthesia infiltration or IVRA) is usually performed for this procedure.

a. Regional anesthesia

Options include a brachial plexus block either at the supraclavicular, infraclavicular, axillary level or blockade of several peripheral nerves.

Neuraxial

Not an option for this type of surgery.

IVRA (Bier's block): Reliable option in a cooperative patient.

a. Benefits: Relatively easy to perform, provides good intraoperative anesthesia, avoids general anesthesia, can be performed in an ambulatory setting.

b. Drawbacks: Not suitable if a longer than usual procedure is planned (more than 45 minutes). Does not provide postoperative analgesia.

c. Issues: Risk of systemic local anesthetic toxicity in case of tourniquet malfunction.

c. Issues: Low but important incidence of neuropathy, not all patients will be suitable for thus type of anesthesia.

d. As discussed previously, some approaches to brachial plexus anesthesia are associated with a risk of pneumothorax and phrenic nerve paresis and are better avoided in patients with significant respiratory disease or morbid obesity.

Local anesthesia

Local anesthesia injection around the site of surgery by the surgeon may also be an option particularly in high risk patients.

c. Monitored anesthesia care

Drawbacks: Requires the presence of experienced personnel in the use of sedation. Some patients are not satisfied with this level of sedation and prefer general anesthetic.

Other issues: Oversedation can lead to apnea and also delay discharge from operating room straight to day ward.

6. What is the author's preferred method of anesthesia technique and why?

The author's preferred choice of anesthetic technique is local anesthetic infiltration or IVRA. Local anesthetic infiltration is advantageous as it minimizes operating room time and can be done safely by the surgeon prior to the surgical technique. It uses relatively low dose local anesthetic and is well tolerated by patients. IVRA is also an excellent choice for this procedure as it provides anesthesia for this minor procedure. The technique is relatively simple to perform and because this is typically a short procedure (less than 30 minutes) the IVRA block lasts for the duration of the procedure. The technique can be performed in the operating room and requires minimal induction time. It is associated with less postoperative nausea and vomiting than a general anesthetic.

What prophylactic antibiotics should be administered?

The decision to administer antibiotics for this procedure will depend on the surgeon performing the procedure. At this time there is insufficient evidence to say whether antibiotics have a routine role in all cases or whether they should be given to patients with other co-morbidities.

What do I need to know about the surgical technique to optimize my anesthetic care?

This procedure can be performed either endoscopically or open. The endoscopic approach involves a device with either one or two portals to release the transverse ligament whereas the open technique involves an incision of approximately 6 cm distally from the distal wrist crease and then release of the transverse ligament directly. The endoscopic technique carries a higher risk of median nerve injury but is associated with a faster return to work time.

What can I do intraoperatively to assist the surgeon and optimize patient care

If the procedure is under regional anesthesia or local anesthetic technique ensure the patient has been fully informed of the procedure and ask the patient if they would like to be sedated then careful monitoring of sedation is required. If the patient wishes to be sedated then careful monitoring of sedation is required. If the patient is having a general anesthetic the usual monitoring of patient is required.

What are the most common intraoperative complications and how can they be avoided/treated?

Tourniquet failure intraoperatively: This may be as a result of uncontrolled hypertension or the actual mechanical tourniquet may not be working properly. This can lead to improper exsanguination as well as a painful limb for the patient, a blood filled field for the operator, and also local anesthetic toxicity if IVRA has been performed.

Careful patient monitoring must include attention to the airway, breathing, and circulation. If IVRA has been performed, evaluate for signs of local anesthetic toxicity, which includes circumoral tingling, metallic taste in the mouth, tinnitus, confusion and seizures. Neurological signs occur prior to cardiovascular signs. For minor symptoms, intravenous midazolam can increase the seizure threshold. If the patient is seizing, he or she requires ventilation, not intubation, unless other airway devices are inadequate.

Every anesthesiology department should have a plan for local anesthetic systemic toxicity (LAST). This plan should incorporate 20% lipid emulsion, which is the antidote for local anesthetic and there should be a supply in close proximity to every site that local anesthetic is being delivered.

Progressive neurological symptoms or cardiovascular symptoms should alert the anesthesiologist to potential LAST and they should ensure the lipid emulsion is close by and considering administering it. There is recent evidence supporting the use lipid emulsion at the early signs of cardiac arrhythmias suspected to be secondary to LAST, prolonged seizures or rapidly evolving symptoms of LAST.

The dose of 20% lipid emulsion is 1.5 mL/kg (lean body mass) administered intravenously over 1 minute, followed by a continuous infusion of 0.25 mL/kg/min given over 30 minutes. If there is persistent cardiovascular collapse, the bolus dose can be repeated every 5 minutes. If blood pressure returns but the patient remains hypotensive, the infusion dose can be doubled. The infusion should be continued for at least 30 minutes. If cardiovascular collapse occurs, the patient will require CPR. If the tourniquet fails or is deflated after 30 minutes, the patient should not experience local anesthetic toxicity.

The authors preferred local anesthetic of choice for IVRA is lidocaine. Lidocaine provides a fast onset time for the block and also because the duration of surgery is usually short lidocaine provides sufficient analgesia and anesthesia for this duration. Because this surgery is not associated with significant postoperative pain a longer acting local anesthetic is not required.

Bupivacaine has a high level of protein binding and therefore it should not be used for IVRA as there is a significant potential for cardiac toxicity when the tourniquet has been deflated. Upper limb brachial plexus blocks whilst very effective are usually not necessary for this procedure. They require personnel who are trained in these techniques and administration of this block if in the operating room can take a substantial amount of time. However the type of anesthetic will depend on the ease of the procedure, surgeon preference as well as anesthesiologist and patient preference.

Complications

Cardiac: Major cardiac complications may be seen in the setting of systemic local anesthetic toxicity. Although a very rare occurrence if all safety steps are followed, the patient may have cardiac arrhythmias and cardiovascular collapse. If this occurs cardiac arrest is imminent and help should be sought. Intravenous lipids should be considered early in the resuscitative efforts.

Pulmonary: Usual pulmonary complications after general anesthetic including respiratory tract infection. If under a supraclavicular block there is a low risk of pneumothorax associated with the block although with ultrasound technique this is unlikely.

a. Neurologic:

Confusion, visual disturbance, slurred speech, and seizures all suggestive of local anesthetic toxicity.

b. If the patient is intubated, are there any special criteria for extubation?

If the patient has a general anesthetic, the usual criteria for extubation apply.

c. Postoperative management

What analgesic modalities can I implement?

Postoperative pain is usually minimal and can usually be managed with acetaminophen, NSAIDs and local anesthetic wound infiltration.

What level bed acuity is appropriate?

This is usually done as a day procedure so if the patient suitable for day procedure they can be discharged when they fulfill all the day care discharge criteria.

What are common postoperative complications, and ways to prevent and treat them?

This is a relatively safe procedure and usually performed under a technique not involving general anesthesia. The most common complication would be postoperative discomfort and postoperative nausea and vomiting.

What's the Evidence?

(This editorial looks at the various anesthesia options for this procedure. It is a well-researched and comprehensive article that gives a well-balanced discussion of each option. The article states that local anesthesia and IVRA are useful and effective forms that take minimal time in comparison to general anesthesia and regional block.

(This article compares the options for elective hand surgery. While carpal tunnel is not included in the list of procedures, the article states the advantages of IVRA as it reduces nursing demands in the PACU and DSU and ultimately allows for faster patient discharge.)

(This gives an excellent overview of carpal tunnel syndrome including the incidence, risk factors, and conditions that are associated with this condition. It discusses the options available for treatment and also the surgical approaches comparing endoscopic and open approaches.)